#include <algorithm>
#include<bits/stdc++.h>
using namespace std;
using db = long double;
const int maxn = 510;
void solve() {
int n, a, b;
cin >> n >> a >> b;
vector<int> vec(n+10);
for (int i = 0; i < n; i++) cin >> vec[i];
vector<vector<db>> dp(n + 10, vector<db>(b + 10, 0));
auto ndp = dp;
dp[0][0] = 1;
for (int i = 0; i < n; i++) {
for (auto &v: ndp) fill(begin(v), end(v), 0);
for (int x = 0; x <= i; x++) {
for (int y = 0; y <= b; y++) {
ndp[x][y] += dp[x][y];
}
for (int y = 0; y <= b - vec[i]; y++) {
ndp[x + 1][y + vec[i]] += dp[x][y] * (x + 1) / (n - x);
}
}
dp = ndp;
}
for (auto &v: ndp) fill(begin(v), end(v), 0);
db ans = 0;
for (int i = 0; i < n; i++) {
ndp = dp;
for (int x = 0; x < n; x++) {
for (int y = 0; y <= b - vec[i]; y++) {
ndp[x + 1][y + vec[i]] -= ndp[x][y] * (x + 1) / (n - x);
}
}
db temp = 0;
for (int x = 0; x < n; x++) {
db t1 = 0;
for (int y = max(0, a - vec[i] + 1); y <= min(a, b - vec[i]); y++) {
t1 += ndp[x][y];
}
temp += t1 / (n - x + 1e-9);
if(temp > 1){
cout <<" cur temp " << temp <<" in " << i <<","<< x <<','<< y << endl;
return;
}
}
ans += temp;
}
cout << fixed << setprecision(30) << (long double) ans << endl;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}